We were stopped at a red light at Hayes and Franklin, trying to make a right turn. The crosswalks were crowded with old people. Lots of gray hair; lots of bald heads. A few had canes; one had a walker.

Some of them couldn't make it across in time, and by then the other crosswalk had filled up. A procession of the old, all streaming in the same direction. It was a little eerie.

I leaned over to Tracy. "Our people," I said.

Because this is our peer group now. We are old. Sometimes we forget that and think that we've been the same person all along, but of course that's only true in some vague cosmic sense. Our bodies have become unreliable. Our brains are somewhat vague and creaky. We really don't like to think about our thinking.

Being old in this society is a little embarrassing. There are lots of stereotypes about us, and lots of contempt from the whippersnappers. We have internalized the negative stereotypes, as all marginalized people do. We long to be something else.

Of course, we have the great consolation of schadenfreude. We know that time will also visit the young and the surly. We know that they will feel what we feel now, and they will say, "Not me. I'm different." Yeah, been there, done that. Doesn't work.

We might even resent other old people. Our society teaches us that we're disposable now. We don't want to feel disposable. In our brains, we separate ourselves from other old people. We see someone with a cane, and we say: At least I don't have a cane.

I knew where the old people were filing off to; I was about to file off there myself. It was a matinee performance of "Show Boat," a quite wonderful San Francisco Opera production. Joshua Kosman gave it a fine review, even if he disliked the second act. And it's true, the first act is where the meat is, musically speaking.

Not that everybody there was old; there were a few kids and a few others under 30. But look out over the audience: a sea of gray. The procession up and down the aisles was very slow. In the stairways leading to the lower level, there was always room down the middle, because everyone was grasping the railings.

Arts people are, of course, aware of their demographics. But, they insist, new audience members will replace the old, even if the median age stays the same. Some old people, after all, have a lot of disposable income. They go on trips; they fix up second homes; they patronize the arts.

And there is art that young people attend; Oakland is full of that sort of thing right now. It's not clear that any of this art will scale up so that people can make a living at it. But it's also not clear whether giant arts organizations can still be profitable.

Traditional arts organizations are closing down. Art is consolidated, which is bad for art. Something like the opera can't survive on ticket sales alone, even if the price of tickets has become astronomical. The opera depends on the kindness of friends and strangers. Are these people getting old?

"Show Boat" is a giant hit of nostalgia for us old people, reminding us of the time when musicals were all the rage; they were popular entertainment. My head was turned by rock 'n' roll, and I didn't really see musicals as a big part of my life. And yet, how come I have all these show tunes in my head?

"Show Boat," I realize, was produced on Broadway 16 years before my birth. It is essentially from my era, even though I remember it as way before my time. And I resist nostalgia; I resist living in the past. As the novelist L.P. Hartley said, "The past is a foreign country. They do things differently there."

Oh, but nostalgia feels so good. Take a wallow in it. Start your sentences with, "I remember when" or "Back in the day." Sit on a bench and remember that time in Chicago with the frogs and the Champagne and the wonderful stranger who stayed only for the night. Come on, lean back. Remember ... high school?

Yeah, it was pretty terrible. It always is. And everyone smoked, and segregation was still prevalent, and no one wore seat belts, and women were chained to a few nonthreatening jobs. Yeah, that was a time. Newspapers delivered by children. American foreign policy dedicated to overthrowing foreign governments and exploiting their resources. Oh, to have lived in that golden age!

It's just life. We're in a different place than we used to be, but it's the same old same old - heartbreak and joy, pain and pleasure. And old man river, he just keeps rolling along.

In which, not for the first time, we realize that we're not special.

"But perhaps it was only sobbing," she thought, and looked into its eyes to see if there were any jcarroll@sfchronicle.com.